Motor malfunction monitoring device, drive motor system and motor malfunction monitoring method

ABSTRACT

The present disclosure relates to a motor malfunction monitoring device, and a drive motor for oilfield operations including: a signal acquisition module configured to acquire operation data of the drive motor, wherein the signal acquisition module comprises a vibration signal acquisition unit and/or an electrical signal acquisition unit, the vibration signal acquisition unit comprises one or more vibration sensors mounted at a component to be detected of the drive motor during use and provided for detecting transverse vibration and/or longitudinal vibration, and/or the electrical signal acquisition unit comprises a voltage sensor and a current sensor for detecting a voltage and a current of the drive motor, respectively; a data storage module storing therein a database of normal operation spectrums created when the drive motor runs normally; and a signal analysis module configured to extract an acquired operation data spectrum of the operation data acquired, compare the acquired operation data spectrum with a respective normal operation data spectrum in the database of normal operation spectrums to obtain a similarity, and determine that the drive motor fails when the similarity is less than a predetermined threshold.

FIELD

The present disclosure generally relates to an apparatus utilized in thefield of oilfield operations, and more specifically, to a motormalfunction monitoring device, a drive motor system and a motormalfunction monitoring method.

BACKGROUND

At present, the electrically-driven apparatus is widely used in thefield of oilfield operations. For example, the electrically-drivenapparatus may be employed for electrically-driven fracturing,electrically-driven mixing, electrically-driven sand mixing,electrically-driven sand transportation, and other engineeringoperations. An electrically-driven apparatus typically includes a motorfor supplying power, equipped with a variable frequency drive (VFD)(also referred to as a drive unit of the motor) regulating the powersource for the motor in frequency and voltage. The VFD includes arectifier, an inverter and a control circuit, where the control circuitdetects operation status of the inverter and the rectifier and controlsan input from the inverter to the motor to protect electrical components(e.g., the motor and the like) of the circuit. The control circuit ofthe VFD can monitor parameters on a current, voltage, and the like, ofthe motor, triggers an alarm when those parameters exceed predeterminednormal threshold ranges, and then cuts off the power supply circuit.

SUMMARY

The objective of the present disclosure is to provide anelectrically-driven apparatus used in a well site with a motormalfunction monitoring device and a motor control system. For anelectrically-driven apparatus used in a well site, due to complicatedmaterial and vibration conditions in the environment, some components ofthe apparatus are vulnerable after a period of time, causing shutdown ofthe electrically-driven apparatus and further incurring huge time andlabor costs. Therefore, there is a necessity to monitor and determine amalfunction for an electrically-drive apparatus used in a well site, andsend a prompt to the same, so as to give engineers a necessary reminderto examine and repair the electrically-driven apparatus.

The motor malfunction monitoring device according to the presentdisclosure cannot only monitor the electrical status of a motor (e.g.,whether a voltage or current is normal, or the like) but also canmonitor status of mechanical components (e.g., bearings, bases, and thelike) of the motor. In the meantime, the motor control system canfurther control the motor based on the above status.

In a first aspect of the present disclosure, there is provided a motormalfunction monitoring device for monitoring a malfunction of a drivemotor in oilfield operations, comprising:

a signal acquisition module configured to acquire operation data of thedrive motor, wherein the signal acquisition motor comprises a vibrationsignal acquisition unit and/or an electrical signal acquisition unit,the vibration signal acquisition unit comprises one or more vibrationsensors for detecting transverse vibration and/or longitudinal vibrationof a component to be detected of the drive motor, and/or the electricalsignal acquisition unit comprises a voltage sensor and a current sensorfor detecting a voltage and a current of the drive motor, respectively;

a data storage module storing therein a normal operation data spectrumlibrary created when the drive motor runs normally; and

a signal analysis module, wherein the signal analysis module isconfigured to extract an acquired operation data spectrum of theoperation data acquired, compare the acquired operation data spectrumwith a respective normal operation data spectrum in the normal operationdata spectrum library to obtain a similarity, determine whether thesimilarity is less than a predetermined threshold, and determine thatthe drive motor fails when the similarity is less than the predeterminedthreshold.

Alternatively, the data storage module stores therein a database formalfunction spectrums created when the drive motor runs at differenttypes of malfunctions, and the motor malfunction monitoring devicefurther comprises a malfunction diagnosis module, and wherein, after thesignal analysis module determines that the drive motor fails, themalfunction diagnosis module compares the acquired operation dataspectrum with malfunction spectrums in the database for malfunctionspectrums and diagnoses a malfunction type of the drive motor.

Alternatively, the data storage module is updated using operation dataand/or the acquired operation data spectrums of the drive motor.

Alternatively, the data storage module expands the normal operation dataspectrum library using the acquired operation data spectrum when thedrive motor does not fail, and expands the database for malfunctionspectrums using the acquired operation data spectrum when the drivemotor fails.

Alternatively, the motor malfunction monitoring device comprises analarming unit, wherein the alarming unit sends a malfunction alarm whenthe motor malfunction monitoring device determines that the drive motorfails.

Alternatively, the component to be detected comprises a bearing and abase of the drive motor.

In a second aspect of the present disclosure, there is further provideda drive motor system, comprising: a drive motor, a variable frequencydrive for regulating an input current to the drive motor and acontroller, characterized by further comprising the motor malfunctionmonitoring device according to any of embodiments of the presentdisclosure, wherein the controller controls, based on a diagnosis resultof the motor malfunction monitoring device, the variable frequency driveto regulate the input current to the drive motor.

Alternatively, for an electrical signal of the drive motor, thecontroller controls the variable frequency drive to switch off the inputcurrent to the drive motor when either of the variable frequency driveand the motor malfunction monitoring device monitors that the drivemotor fails.

In a third aspect of the present disclosure, there is also provided amotor malfunction monitoring method for monitoring a malfunction of adrive motor for oilfield operations, characterized by comprising stepsof:

acquiring operation data of the drive motor, wherein the operation datacomprise a transverse and/or a longitudinal vibration signal of acomponent to be detected of the drive motor, and/or a voltage and acurrent signal of the drive motor;

extracting an acquired operation data spectrum of the operation dataacquired; and

comparing the acquired operation data spectrum with a pre-stored,respective normal operation data spectrum in a normal operation dataspectrum library of the drive motor to obtain a similarity, anddetermining that the drive motor fails when the similarity is less thana predetermined threshold.

Alternatively, the motor malfunction monitoring method furthercomprises:

when determining that the drive motor fails, comparing the acquiredoperation data spectrum with malfunction spectrums in a database formalfunction spectrums pre-stored created when the drive motor runs atdifferent types of malfunctions, and diagnosing a malfunction type ofthe drive motor.

Alternatively, the motor malfunction monitoring method furthercomprises:

storing the operation data and/or the acquired operation data spectrumof the drive motor.

Alternatively, the motor malfunction monitoring method furthercomprises:

expanding the normal operation data spectrum library using the acquiredoperation data spectrum when the drive motor does not fail, andexpanding the database for malfunction spectrums using the acquiredoperation data spectrum when the drive motor fails.

BRIEF DESCRIPTION OF THE DRAWINGS

For the sake of better understanding on the above and other objectives,features, advantages, and functions of the present disclosure, thepreferred embodiments are provided with reference to the drawings. Thesame reference symbols refer to the same components throughout thedrawings. It would be appreciated by those skilled in the art that thedrawings are merely provided to illustrate preferred embodiments of thepresent disclosure, without suggesting any limitation to the protectionscope of the present application, in which

FIG. 1 schematically illustrates a motor malfunction monitoring deviceaccording to an embodiment of the present disclosure;

FIG. 2 schematically illustrates a motor malfunction monitoring deviceaccording to another embodiment of the present disclosure;

FIG. 3 schematically illustrates a motor malfunction monitoring methodaccording to an embodiment of the present disclosure; and

FIG. 4 schematically illustrates a motor malfunction monitoring methodaccording to another embodiment of the present disclosure.

A LIST OF REFERENCE SIGNS

-   -   10, 10′ motor malfunction monitoring device    -   1, 1′ signal acquisition module    -   11, 11′ vibration signal acquisition unit    -   12, 12′ electrical signal acquisition unit    -   2, 2′ data storage module    -   21, 21′ database of normal operation spectrums    -   22′ database for malfunction spectrums    -   3, 3′ signal analysis module    -   4, 4′ malfunction diagnosis module

DETAILED DESCRIPTION OF EMBODIMENTS

Reference now will be made to the drawings to describe in detail theembodiments of the present disclosure. What will be described hereinwill only involve preferred embodiments of the present disclosure, aswell as other manners conceivable for those skilled in the art on thebasis of the preferred embodiments of the present disclosure, which alsofall into the scope claimed by the present disclosure.

The motor malfunction monitoring device as described therein isgenerally provided for monitoring malfunctions of a drive motor used inoilfield operations. FIG. 1 schematically illustrates a modularstructure diagram of a motor malfunction monitoring device 10 accordingto an embodiment of the present disclosure. As shown in FIG. 1, themotor malfunction monitoring device 10 includes a signal acquisitionmodule 1, a data storage module 2 and a signal analysis module.Specifically, the signal acquisition module 1 is responsible foracquiring operation data during the operation of the drive motor, wherethese operation data include an electrical signal of the drive motor,namely a current or voltage signal, and/or vibration signal ofcomponents to be detected. To this end, the signal acquisition module 1may include an electrical signal acquisition unit 12 and/or a vibrationsignal acquisition unit 11, where the electrical signal acquisition unit12, for example, can include voltage sensor(s) and current sensor(s) andbe mounted at appropriate positions of the drive motor, as disclosed inthe prior art, to detect and acquire the voltage signal and currentsignal of the drive motor. In addition, the vibration signal acquisitionunit 11 may include one or more vibration sensors, where, depending oncomponents of the drive motor and vibration directions to be detected,the vibration sensors may be mounted at the components to be detected,particularly along specific directions of the vibration, such that thevibration sensors can detect and acquire the vibration signals of thecomponents in the specific directions. Within the scope of the presentdisclosure, since components of the drive motor often vibrate intransverse and longitudinal directions in case of failure, the vibrationsignal acquisition unit 11 is used to mainly acquire vibration in thetransverse and longitudinal directions. It is noted that, within thescope of the present disclosure, “a transverse direction” refers to adirection parallel to a mounting plane of the drive motor andperpendicular to a longitudinal direction of the drive motor, and “alongitudinal direction” refers to a direction perpendicular to both ofthe mounting plane and the longitudinal direction of the drive motor.For example, within the scope of the present disclosure, depending onthe components concerned and need to be detected, the vibration sensorsof the vibration signal acquisition unit 11 may be mounted at thebearings and the bases of the drive motor to detect and acquirevibration of the bearings and the bases, for detecting whether there isabnormality, loosening or damage of the bearings, loosening of bases,and the like.

Although the vibration signal acquisition unit, for example, includesvibration sensors mounted at the bearings of the drive motor and thebases of the drive motor, as described above, vibration sensors may bemounted at other components of the drive motor, depending on thedifferent components need to be detected and concerned, which also fallinto the scope of the present disclosure.

The data storage module 2 of the motor malfunction monitoring device 10stores therein a database 21 of normal operation spectrums during thenormal operation of the drive motor. Specifically, the database 21 ofnormal operation spectrums includes therein operation data spectrumswhen the drive motor runs normally in different operating conditions,for example, transverse vibration signal spectrums, longitudinalvibration signal spectrums, voltage or current signal spectrums, and thelike, of the components to be detected.

The signal analysis module 3 of the motor malfunction monitoring device10 can perform processing and analysis on the operation data acquired bythe signal acquisition module 1, extract acquired operation dataspectrums of the acquired operation data, and then compare them withcorresponding normal operation spectrums in the database to obtain asimilarity therebetween. If the similarity is lower than a predeterminedthreshold, the signal analysis module determines that the drive motorfails. Specifically, for example, when the signal acquisition module 1has acquired the current or voltage signals and the transverse andlongitudinal vibration signals when the drive motor runs in a certainoperating condition, the signal analysis module extracts spectrums ofthese signals and compares them with the current or voltage signalspectrums and the transverse and longitudinal vibration signal spectrumsat the bearing when the drive motor runs normally in the correspondingoperating condition to obtain a similarity therebetween. If thesimilarity is lower than a predetermined threshold, it is determinedthat the drive motor fails. The predetermined threshold as mentionedabove may be predetermined based on factors, such as the operatingstatus of the drive motor and the like.

FIG. 2 schematically illustrates a motor malfunction monitoring device10′ according to another embodiment of the present disclosure. To avoidduplication, only differences between the embodiments as shown in FIG. 2and the one in FIG. 1 will be described below. In order to differentiatethe two embodiments, the reference symbols involved in FIG. 2 arerepresented with an additional Superscript “′”, as compared with thosein FIG. 1. As shown in FIG. 2, in addition to the modules in FIG. 1, themotor malfunction monitoring device 10′ further includes a malfunctiondiagnosis module 4′. To be specific, when the signal analysis module 3determines that the drive motor fails, the malfunction diagnosis module4′ further determines the malfunction type of the drive motor. Withrespect to the motor malfunction monitoring device 10′ in theembodiment, the data storage module 2′ further stores therein a database22′ for malfunction spectrums when the drive motor runs at differenttypes of malfunctions, and the malfunction diagnosis module 4′ comparesthe acquired operation data spectrums with the malfunction spectrums inthe database and diagnoses the malfunction type of the drive motor.Specifically, the database 22′ of malfunction spectrums stored in thedata storage module 2′ at least includes characteristic spectrums ofoperation data when the drive motor fails at different operatingconditions, for example, characteristic spectrums of the drive motorwhen bearings, bases, or stator coils are loose, short circuit occursbetween stator winding turns, and the like. The malfunction diagnosismodule 4′ compares the acquired operation data with those malfunctionspectrums to find out a malfunction spectrum mostly similar to theacquired operation data, and then determines the specific malfunctiontype of the drive motor.

Alternatively, within the scope of the present disclosure, the datastorage module 2, 2′ is configured to store operation data and/oracquired operation data spectrums of the drive motor. Those spectrumsmay be stored in a local or remote memory of the data storage module 2,2′, which can be implemented by means of existing storage technique inthe related fields. In this circumstance, alternatively, in someembodiments, the data storage module 2, 2′ can further update and expandthe database stored therein (i.e., the database of normal operationspectrums and the database for malfunction spectrums) by using operationdata and/or acquired operation data spectrums of the drive motor.Specifically, the data storage module 2, 2′ expands and updates thedatabase of normal operation spectrums by using the acquired operationdata spectrums when the drive motor does not fail, and expands andupdates the database for malfunction spectrums by using the acquiredoperation data spectrums when the drive motor fails. More specifically,the acquired operation data spectrums are respectively categorizedaccording to the malfunction categories into which they fall.

Alternatively, in some embodiments of the present disclosure, the motormalfunction monitoring device 10, 10′ may further include an alarmingunit which can send out an alarm based on the malfunction determined bythe motor malfunction monitoring device 10, 10′, more specifically, arespective malfunction alarm (e.g., warning light, alarm sound, alarminformation, or the like) corresponding to the malfunction type.

In the present disclosure, there is further provided a drive motorsystem, including: a drive motor, a variable frequency drive (alsoreferred to as drive unit) that can regulate the current or voltage ofthe drive motor, a motor malfunction monitoring device and a controller,where the motor malfunction monitoring device can be configured in theform of the motor malfunction monitoring device 10, 10′ according to anyof the embodiments of the present disclosure. The controller controlsthe drive motor, based on the drive motor's malfunction informationobtained by the motor malfunction monitoring device 10, 10′ (i.e.presence or absence of a malfunction in the drive motor and/or themalfunction type of the drive motor). For example, in some malfunctions,the controller stops the drive motor. It is noted that, under thiscircumstance, the variable frequency drive monitors the current andvoltage of the drive motor as mentioned in the prior art, but since themotor malfunction monitoring device is included in the presentdisclosure, the variable frequency drive may be configured to onlyregulate the input current to the drive motor under the control of thecontroller, without the necessity to monitor the current and voltage ofthe drive motor.

In addition, within the scope of the present disclosure, the variablefrequency drive is configured as a conventional variable frequency driveemployed in the related technical fields of drive motors, which mayinclude a rectifier, an inverter, a control circuit assembly fordetecting the current or voltage of the drive motor and regulating aninput current to the drive motor, and the like. Specifically, thecontroller controls, based on the malfunction of the drive motordetermined by the motor malfunction monitoring device 10, 10′, thevariable frequency drive to regulate an input current or voltage to thedrive motor.

Alternatively, in some embodiments of the present disclosure, for theelectrical signals (i.e., current or voltage) of the drive motor, whenone of the variable frequency drive and the motor malfunction monitoringdevice 10, 10′ monitors an electrical signal malfunction (i.e.,abnormality), the controller controls the variable frequency drive tocut off the input current to the drive motor. In other words, if thevoltage or current malfunction cannot be detected due to failure of thevariable frequency drive or one of the voltage sensor and the currentsensor in the motor malfunction monitoring device, the controller canswitch off the input current to the drive motor for the sake ofsecurity, rather than performing control based on the monitored resultfrom one of the above. Such redundant determination avoids thedeficiency of misjudging the malfunction of the drive motor due tocircuit failure in the variable frequency drive.

FIG. 3 schematically illustrates a flowchart of a motor malfunctionmonitoring method according to the present disclosure. The motormalfunction monitoring method involved herein is particularly used tomonitor a malfunction of a drive motor in oilfield operations, includingsteps of:

S101: acquiring operation data of the drive motor, where the operationdata include a transverse and/or a longitudinal vibration signal ofcomponents to be detected of the drive motor, and/or an electricalsignal, namely a voltage or current signal, of the drive motor;

As aforementioned, depending on different components need to bedetected, the transverse and longitudinal vibration signals at thebearings and the bases of the drive motor may be acquired, to detect andacquire vibration of the bearings and bases of the drive motor forsubsequent determination of a malfunction, such as abnormality,loosening or damage of the bearings, loosening of bases, and the like.

S102: extracting acquired operation data spectrums of the operation dataacquired;

Specifically, the operation data acquired are processed and analyzed,and the acquired operation data spectrums of the operation data acquiredare extracted.

S103: comparing the acquired operation data spectrums with normaloperation data spectrums pre-stored in the database of normal operationspectrums of the drive motor to obtain a similarity, and determines thatthe drive motor fails when the similarity is less than a predeterminedthreshold.

Specifically, the database of normal operation spectrums during thenormal operation of the drive motor is pre-stored. More specifically,the database of normal operation spectrums includes operation dataspectrums (e.g., transverse vibration signal spectrums, longitudinalvibration signal spectrums, voltage or current signal spectrums, and thelike, of components to be detected) when the drive motor runs normallyunder different operating conditions.

In other words, for example, after the current or voltage electricalsignals and transverse and longitudinal vibration signals at thebearings under a certain operating condition of the drive motor areacquired, the spectrums of these signals are extracted and compared withthe current or voltage signal spectrums and the transverse andlongitudinal signal spectrums in the corresponding normal operatingcondition to obtain a similarity therebetween, and it is determined thatthe drive motor fails if the similarity is less than a predeterminedthreshold. The predetermined threshold as mentioned above may bepredetermined based on factors, such as the use status of the drivemotor and the like.

FIG. 4 schematically illustrates a flowchart of a motor malfunctionmonitoring method according to another embodiment of the presentdisclosure, where steps S201 to S203 are identical with those in FIG. 3,which are omitted herein.

In addition, the motor malfunction monitoring method as shown in FIG. 4further includes steps of:

S204: when determining that the drive motor fails, comparing theacquired operation data spectrums with the malfunction spectrumspre-stored in the database for malfunction spectrums under differentmalfunction types of the drive motor, and diagnosing a malfunction typeof the drive motor.

Specifically, determining that the drive motor fails further includesdetermining a malfunction type of the drive motor. The database formalfunction spectrums created when the drive motor fails at differenttypes of malfunctions is pre-stored, including at least characteristicspectrums of operation data when the drive motor fails at differentoperating conditions, for example, characteristic spectrums of the drivemotor when bearings, bases, or stator coils are loose, short circuitoccurs between stator winding turns, and the like. Then, the acquiredoperation data spectrums are compared with those malfunction spectrums,to determine malfunction spectrums mostly corresponding to the acquiredoperation data spectrums and thus determine a specific malfunction typeof the drive motor.

Alternatively, in some embodiments of the present disclosure, the motormalfunction monitoring method further includes a step of:

storing operation data and/or the acquired operation data spectrums ofthe drive motor.

In other words, the database of normal operation spectrums and thedatabase for malfunction spectrums can be updated and expanded by usingthe operation data and/or the spectrums of the acquired operation dataof the drive motor. The database of normal operation spectrums isexpanded and updated by using the acquired operation data spectrums whenthe drive motor does not fail, while the database for malfunctionspectrums is expanded and updated by using the acquired operation dataspectrums when the drive motor fails. More specifically, the acquiredoperation data spectrums are categorized according to the malfunctioncategories into which they fall.

The above description on multiple embodiments of the present disclosureis provided to the ordinary skilled in the related field forillustration, without any intention to be exclusive or limited to asingle embodiment of the present disclosure. Given the teaching, theordinary skilled in the art would envision multiple types ofsubstitution and variation of the present disclosure. Therefore,although some alternative embodiments are described herein, the ordinaryskilled in the art would understand or easily devise other embodiments.The present disclosure intends to cover all substitution, modificationand variation of the embodiments described herein, as well as otherembodiments falling within the spirits and scope described above.

I/We claim:
 1. A motor malfunction monitoring device (10, 10′) formonitoring a malfunction of a drive motor in oilfield operations,comprising: a signal acquisition module (1, 1′) configured to acquire anoperation data of the drive motor, wherein the signal acquisition module(1, 1′) comprises a vibration signal acquisition unit (11, 11′) and/oran electrical signal acquisition unit (12, 12′), the vibration signalacquisition unit (11, 11′) comprises one or more vibration sensors fordetecting transverse vibration and/or longitudinal vibration ofcomponents to be detected of the drive motor, and/or the electricalsignal acquisition unit (12, 12′) comprises a voltage sensor and acurrent sensor for detecting a voltage and a current of the drive motor,respectively; a data storage module (2, 2′) storing therein a database(21, 21′) of normal operation spectrums during a normal operation of thedrive motor; and a signal analysis module (3, 3′) configured to extractacquired operation data spectrums of the acquired operation data,compare the acquired operation data spectrums with corresponding normaloperation spectrums to obtain a similarity, wherein when the similarityis lower than a predetermined threshold, determine that the drive motorfails.
 2. The motor malfunction monitoring device (10′) according toclaim 1, wherein the data storage module (2′) stores therein a databaseof malfunction spectrums (22′) of different types of malfunctions of thedrive motor, and the motor malfunction monitoring device (10′) furthercomprises a malfunction diagnosis module (4′), wherein, when the signalanalysis module (3′) determines that the drive motor fails, themalfunction diagnosis module (4′) compares the acquired operation dataspectrums with the malfunction spectrums and determine a malfunctiontype of the drive motor.
 3. The motor malfunction monitoring device(10′) according to claim 2, wherein the data storage module (2, 2′) isupdated with the operation data and/or the acquired operation dataspectrums of the drive motor.
 4. The motor malfunction monitoring device(10′) according to claim 3, wherein the data storage module (2, 2′)expands the database of normal operation spectrums with the acquiredoperation data spectrums in the normal operation of the drive motor, andexpands the database for malfunction spectrums with the acquiredoperation data spectrums in the malfunction of the drive motor.
 5. Themotor malfunction monitoring device (10, 10′) according to claim 1,wherein the motor malfunction monitoring device (10, 10′) comprises analarming unit, wherein the alarming unit sends out an alarm when themotor malfunction monitoring device (10, 10′) determines that the drivemotor fails.
 6. The motor malfunction monitoring device (10, 10′)according to claim 2, wherein the motor malfunction monitoring device(10, 10′) comprises an alarming unit, wherein the alarming unit sendsout an alarm when the motor malfunction monitoring device (10, 10′)determines that the drive motor fails.
 7. The motor malfunctionmonitoring device (10, 10′) according to claim 3, wherein the motormalfunction monitoring device (10, 10′) comprises an alarming unit,wherein the alarming unit sends out an alarm when the motor malfunctionmonitoring device (10, 10′) determines that the drive motor fails. 8.The motor malfunction monitoring device (10, 10′) according to claim 4,wherein the motor malfunction monitoring device (10, 10′) comprises analarming unit, wherein the alarming unit sends out an alarm when themotor malfunction monitoring device (10, 10′) determines that the drivemotor fails.
 9. The motor malfunction monitoring device (10, 10′)according to claim 1, wherein the components to be detected comprisebearings and bases of the drive motor.
 10. A drive motor system,comprising: a drive motor, a variable frequency drive for regulating aninput current to the drive motor and a controller, wherein the drivemotor system further comprises the motor malfunction monitoring device(10, 10′) according to claim 1, wherein the controller controls, basedon a determining result of the motor malfunction monitoring device (10,10′), the variable frequency drive to regulate the input current to thedrive motor.
 11. The drive motor system according to claim 10, wherein,for the electrical signal of the drive motor, the controller controlsthe variable frequency drive to cut off the input current when either ofthe variable frequency drive and the motor malfunction monitoring device(10, 10′) determines that the drive motor fails.
 12. A motor malfunctionmonitoring method for monitoring a malfunction of a drive motor inoilfield operations, comprising steps of: acquiring operation data ofthe drive motor, wherein the operation data comprises a transverseand/or a longitudinal vibration signal of components to be detected ofthe drive motor, and/or a voltage and a current signal of the drivemotor (S101, S201); extracting acquired operation data spectrums of theacquired operation data (S102, S202); and comparing the acquiredoperation data spectrums with corresponding normal operation spectrumsin a pre-stored database of normal operation spectrums during the normaloperation of the drive motor, to obtain a similarity, wherein when thesimilarity is lower than a predetermined threshold, determine that thedrive motor fails (S103, S203).
 13. The motor malfunction monitoringmethod according to claim 12, wherein the motor malfunction monitoringmethod further comprises: when determining that the drive motor fails,comparing the acquired operation data spectrums with malfunctionspectrums in a database comprising malfunction spectrums of differenttypes of malfunctions of the drive motor, and determining a malfunctiontype of the drive motor (S204).
 14. The motor malfunction monitoringmethod according to claim 13, wherein the motor malfunction monitoringmethod further comprises a step of: storing the operation data and/orthe acquired operation data spectrums of the drive motor.
 15. The motormalfunction monitoring method according to claim 14, wherein the motormalfunction monitoring method further comprises a step of: expanding thedatabase of normal operation spectrums with the acquired operation dataspectrums in the normal operation of the drive motor, and expanding thedatabase for malfunction spectrums with the acquired operation dataspectrums in the malfunction of the drive motor.